3GPP (3rd Generation Partnership Project) specifies a protocol used between base stations and mobile stations in order to standardize communication between the base stations and mobile stations. For example, 3GPP specifies PDCP for executing concealment of data, data compression, and the like and RLC for executing retransmission control, duplicate detection, and the like between the base stations and mobile stations.
It is assumed in a configuration of a communication system specified by 3GPP that processes in the PDCP (Packet Data Control Protocol) layer and processes in the RLC (Radio Link Control) layer are executed by the same device. To be more specific, data used in the PDCP layer and the RLC layer is stored in a common buffer, and execution of the processes in the PDCP layer and execution of the processes in the RLC layer are synchronized.
In recent years, 3GPP has been examining a configuration regarding Small Cells (dual connectivity). It is assumed in the configuration regarding Small Cells that the processes in the PDCP layer and the processes in the RLC layer are performed by physically separate devices. Non Patent Literature 1 discloses a configuration of